Using a DSLR to Study Variable Stars

Canon 450D - linear over a magnitude using RAW images with a specific setting

Canon 85 mm fixed lens- can be used to do precise estimates down to magnitude 8 ( undriven ).

Canon 200 mm fixed lens- can be used to do precise estimates down to magnitude 10 ( undriven ).

Precision Photometry Eye: +/- 0.1 m Standard DSLR Photometry: +/- 0.03m Precise DSLR Photometry: +/- 0.01m

Precision Photometry The right settings for the right signal to noise ratio (SNR -100)

Precision Photometry Epsilon Aurigae & 85 mm lens: Exposure 5 secs,ISO 200, f5 Exposure 5 secs, ISO 200, f4.5 Exposure 5 secs:ISO 200. f4.

Precision Photometry Centered target stars The effect of wind Remote Switch Careful Focus Long Exposure Dark Frames

Standard DSLR Photometry +/- 0.03m ten images analysed

200 mm lens - exposure 3.2 secs, f2.8, ISO 800 images every ten/fifteen minutes

85 mm lens, exp 5 secs, f3.5, ISO 800

200 mm lens - exposure 2.5 secs, f2.8, ISO 800

Variations of 0.2/0.3 magnitude - a new world of variables

Precision DSLR Photometry +/- 0.01m thirty/ fifty images analysed

Estimates of the 20/2/10 JD: Camera Settings with an 85 mm lens: Exposure-5 seconds, ISO 200, f4. 5 sets of ten images: Analysed with AIP4WIN v (1) 3.776V (2) 3.777V (3) 3.774V (4) 3.769V (5) 3.781V Average = 3.775V Standard Deviation = 0.004

AIP4WIN - analysis of RAW images

Dark frames Flat Fields

Multi-image deep sky stacking procedure - 30 minutes to analyse 50 images

V Photometry Green Channel Images Transformation Co-efficient

Estimates of the 10/3/10 JD: Camera Settings with an 85 mm lens: Exposure-5 seconds, ISO 200, f4. 5 sets of ten images: Analysed with AIP4WIN v (1) 3.769V (2) 3.760V (3) 3.776V (4) 3.764V (5) 3.758V Average = 3.765V Standard Deviation = 0.007

Deciphering Epsilon Aurigae

Presentation of estimates

DSLR Cameras - not as sensitive as CCD cameras because they are not cooled - but yield just as good results down to mag 10.5